The construction of the deep-buried tunnels of the Sichuan-Tibet railway is facing severe rockburst disasters. Pressure relief boreholes and rock bolt support are effective methods for mitigating rockburst in hard rock. However, the mechanisms and differences in control effectiveness of these methods for different types of rockburst have yet to be revealed. This paper presents the results of two true triaxial unloading rockburst tests: Static-driven rockburst (static tests) due to excavation disturbance and dynamic-triggered rockburst (dynamic tests) due to adjacent tunnel excavation. The rockburst samples include intact granite, granite with a borehole (hole-granite), and granite with a negative Poisson's ratio bolt (bolt-granite). The mitigation mechanisms of the borehole and bolt were investigated in terms of rockburst intensity, failure patterns, and acoustic emission precursors. The results show that borehole and bolt inhibit the formation of a shear fracture plane during rockburst, with the bolt's inhibition effect being more pronounced. For static tests, borehole and bolt significantly reduce rockburst intensity, with the reduction being more significant for bolt-granite. The bolt mainly inhibits the propagation and penetration of shear microcracks. In contrast, the borehole promotes the propagation of shear microcracks. However, for dynamic tests, the rockburst intensity of bolt-granite is equivalent to that of intact granite, while the borehole enhances the rockburst intensity. The bolt inhibits the final buckling crack penetration in dynamic tests, while the borehole promotes slabbing. For static and dynamic tests, the borehole has little influence on precursor indicators, while the bolt increases the difficulty of precursor capture. Generally, the pressure relief borehole is more effective in controlling static tests, while bolt-reinforced support has advantages in dynamic test control.

中文翻译：

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泄压钻孔和锚杆支护岩爆缓解机制：花岗岩真三轴卸载岩爆试验的见解


川藏铁路深埋隧道建设面临严重岩爆灾害。泄压钻孔和锚杆支护是缓解硬岩岩爆的有效方法。然而，这些方法对不同类型岩爆的控制效果的机制和差异尚待揭示。本文介绍了两种真正的三轴卸载岩爆试验的结果：由于开挖扰动引起的静态驱动岩爆（静态试验）和由于邻近隧道开挖引起的动态触发岩爆（动态试验）。岩爆样品包括完整的花岗岩、带有钻孔的花岗岩（孔洞花岗岩）和带有负泊松比螺栓的花岗岩（螺栓花岗岩）。从岩爆强度、破坏模式和声发射前兆方面研究了钻孔和锚杆的缓解机制。结果表明，钻孔和锚杆抑制岩爆过程中剪切断裂面的形成，其中锚杆的抑制效果更为明显。对于静态试验，钻孔和锚杆显着降低了岩爆强度，其中锚杆花岗岩的降低更为显着。螺栓主要抑制剪切微裂纹的扩展和渗透。相反，钻孔促进了剪切微裂纹的扩展。然而，对于动态测试，锚杆花岗岩的岩爆强度与完整花岗岩相当，而钻孔增强了岩爆强度。在动态测试中，螺栓抑制了最终的屈曲裂纹渗透，而钻孔则促进了板裂。对于静态和动态测试，钻孔对前兆指标的影响很小，而锚杆则增加了前兆捕获的难度。 一般来说，泄压钻孔在控制静态试验方面更有效，而锚杆加固支护在动态试验控制方面更有优势。